What are the three major methods of rhenium powder production

Rhenium powder production refers to the metallurgical process of producing metallic rhenium powder from pure rhenium compounds. Rhenium compounds commonly used in the production of rhenium powder include Ammonium perrhenate, Potassium perrhenate, Rhenium(VII) oxide and Rhenium pentachloride. The production methods include hydrogen reduction method, electrolysis method, and halide thermal ionization method. The method of reducing Ammonium perrhenate with hydrogen is commonly used in industry.

Hydrogen reduction method:

Put Ammonium perrhenate or Potassium perrhenate in a tubular reduction furnace for hydrogen reduction, which is usually carried out in two times. The first reduction temperature of Ammonium perrhenate is 573-623K, and the second reduction temperature is 1073-1223K. The first reduction temperature of Potassium perrhenate is 773-823K, and the second reduction temperature is 1173-1273K. The purity of rhenium powder depends on the purity of raw materials. When the purity of Ammonium perrhenate is more than 99.99%, the purity of rhenium powder can reach 99.99% 99%. Particle size can be less than 2.5 μ M. Rhenium powder made from Potassium perrhenate contains a large amount of potassium, that is, after washing with water and dilute hydrochloric acid, it still contains a few dry parts of potassium, with a purity of only 99%. This rhenium powder is not suitable for deep processing. Therefore, the method of reducing Potassium perrhenate raw materials with hydrogen has been eliminated. Pure rhenium powder can also be obtained by reducing Rhenium(VII) oxide with hydrogen, but the cost is high

Electrolytic method:

The process of preparing metallic rhenium powder from Ammonium perrhenate or Potassium perrhenate aqueous solution by aqueous solution electrolysis. Electrolysis is carried out in an electrolytic cell with platinum sheets as the anode and tantalum sheets as the cathode. The mass concentration (g/L) of some components of electrolyte is: Ammonium perrhenate 100, ammonium sulfate 60, sulfuric acid 100; Alternatively, potassium hyperzincate 50, ammonium sulfate 40, and sulfuric acid 75 are used, with a current density of 1A/cm2 and an electrolysis temperature of 343K to maintain circulation and stable concentration of the electrolyte. Rhenium powder is regularly peeled from the cathode tantalum sheet. The prepared rhenium powder was washed with alcohol and dried, and then treated in hydrogen gas at a temperature of 1073K. The particle size of rhenium powder in the product is relatively coarse, mostly greater than 4 μ m. Not suitable as a raw material for producing dense rhenium using powder metallurgy method. Fine rhenium powder can be obtained by electrolysis using a rotating cathode. The electrolysis method is generally used for rhenium plating on metal surfaces.

Halide thermal ionization method:

Rhenium halides can be thermally dissociated to obtain metallic rhenium. Using inert gas as a carrier, ReCl5 with a boiling point of 603K is brought into a heat-resistant glass chamber. ReCl5 undergoes thermal dissociation reaction when it encounters tungsten or molybdenum wire heated to 1473-1573 under vacuum in the heat-resistant glass chamber. Metal rhenium is deposited on the tungsten or molybdenum wire, and the gas products of the reaction can be returned for use. This method is mainly used for rhenium plating on tungsten molybdenum products.